Topic
Turbofan
About: Turbofan is a research topic. Over the lifetime, 4114 publications have been published within this topic receiving 39490 citations. The topic is also known as: fanjet & turbofan engine.
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01 Feb 1977
TL;DR: In this paper, an improved method for predicting both direct and indirect combustion noise from aircraft engines is developed and experimentally evaluated by conducting rig experiments and by comparing with data from several full scale engines.
Abstract: : Improved methods for predicting both direct and indirect combustion noise from aircraft engines are developed and experimentally evaluated by conducting rig experiments and by comparing with data from several full scale engines. Comparison of predictions with full scale engine data indicated that direct combustion noise is the dominant source for the P and WA engines investigated. The direct combustion noise prediction system includes expressions for acoustic power level, peak frequency and full-scale engine acoustic transmission loss due to combustor/duct coupling and turbine attenuation. These expressions are derived in terms of readily available performance and geometry parameters from the burner and turbine. New parameters introduced by the prediction system include the effects of fuel nozzle number and burner length. Predictions are shown to be in good agreement with data obtained from component rig tests on several JT8D type burner configurations (including single and multiple fuel nozzle, conventional and low emission designs). In addition, when transmission losses are accounted for, the predictions are also shown to be in good agreement with observed combustion noise levels and peak frequencies from four P and WA turbofan engines (i.e. the JT8D-109, JT9D-7A, JT9D-70 and the prototype JT10D). Predicted combustion noise directivity patterns and spectra shapes are determined empirically, using the data from both the rig tests and these four engines. Results from the analytical and experimental combustion noise investigations are used to identify combustion noise reduction methods obtainable through modifications in burner design and/or performance parameters.
22 citations
01 Jan 1975
TL;DR: In this article, data and engine parts on in-service JT3D and JT8D engines were analyzed and documented relative to engine deterioration and it was concluded that the fan-compressor system of these engines contributes to the long term engine deterioration.
Abstract: Data and engine parts on in-service JT3D and JT8D engines were analyzed and documented relative to engine deterioration. It is concluded that the fan-compressor system of these engines contributes to the long term engine deterioration. An engine test and instrumentation plan was formulated for a proposed follow-on program. The goal of this program is to verify the above conclusion and to attempt to identify more precisely which components of the fan-compressor system are at fault.
22 citations
TL;DR: In this article, some exergetic measures are calculated for a JT8D turbofan engine at takeoff, including fuel depletion ration, productivity lack ratio, fuel exergy factor, product exergy factors and improvement potential rates.
Abstract: In this article, some exergetic measures are calculated for a JT8D turbofan engine at takeoff. Selected exergetic measures in this study are as follows: fuel depletion ration, productivity lack ratio, fuel exergy factor, product exergy factor and improvement potential rates. The engine has low-pressure compressor (LPC) stages, high pressure compressor (HPC) stages, a single HP turbine (HPT), and finally three LPT stages. The exergetic assessment of the JT8D turbofan components provided here should be helpful for designing turbofan engines. Results from this study also evaluate effects of the maximum power setting on the exergetic measures of the engine components commonly used in medium range commercial aircrafts.
22 citations
01 Aug 1973
TL;DR: In this article, an investigation was conducted to determine the aerodynamic characteristics of a large-scale subsonic jet transport model with an upper surface blowing flap system that would augment lift.
Abstract: An investigation has been conducted to determine the aerodynamic characteristics of a large-scale subsonic jet transport model with an upper surface blowing flap system that would augment lift. The model had a 25 deg swept wing of aspect ratio 7.89 and two turbofan engines with the engine centerline located at 0.256 of the wing semispan. The lift of the flap system was augmented by turbofan exhaust impingement on the Coanda surface. Results were obtained for several flap deflections and engine nozzle configurations at jet momentum coefficients from 0 to 4.0. Three-component longitudinal data are presented with two engines operating. Limited longitudinal and lateral data are presented with an engine out. In addition, limited exhaust and flap pressure data are presented.
22 citations
TL;DR: In this article, a switched controller is proposed for a two-spool turbofan engine to achieve overshoot-free speed control, where the real-time data provided by the component level model and the equilibrium manifold are used in the design process.
22 citations